Typical cables include a conductor, such as a number of copper or aluminum strands, surrounded by an insulation layer. In some instances, the life span of a cable is shortened when water enters the cable and forms micro-voids in the insulation layer around ionic contaminants. These micro-voids spread throughout the insulation layer in a tree like shape, collections of which are sometimes referred to as water trees.
Water trees are known to form in the insulation layer of electrical cables when medium or high voltage is applied to the cable in the presence of water and ions. As water trees grow, they compromise the dielectric properties of the insulation layer until failure occurs. Many large water trees initiate at the site of an imperfection or a contaminant, but contamination is not a necessary condition for water trees to propagate.
Water tree growth can be eliminated or retarded by removing or minimizing the water or ions, or by reducing the voltage stress. Another approach requires the injection of a dielectric enhancement fluid into interstices located between the strands of the cable. However, when a dielectric enhancement fluid, or any other fluid such as strand blocking fluid, etc., is injected into the cable, it can leak from the cable, particularly during heat cycling. In that regard, during heat cycling, the insulation layer becomes soft and releases its tension on sealing devices, such as O-ring seals, in the cable connection assembly. As the tension is released, the seals may fail and allow dielectric enhancement fluid to leak from the cable.
Accordingly, there exists a need for cable connection assemblies having improved seals to decrease leak points of injected fluid from the insulation layer. Such improved seals may also decrease water entry points into the cable.